1. Field of the Invention
This invention relates to a process for treating halide contaminated waste using a reductone, more particularly to a process for treating carbon tetrachloride using ascorbic acid.
2. Description of the Related Art
In the past, because carbon tetrachloride is stable and nonflammable, it was widely used as a solvent for manufacturing a dry cleaning agent, an adhesive for semiconductors, a cleaning agent for mechanical elements, etc. However, according to the classification of carcinogens by the International Agency for Research on Cancer, carbon tetrachloride is possibly carcinogenic to humans. In Taiwan, there are many ground water sites which are contaminated by chlorine-containing organic solvents, such as carbon tetrachloride. It is known that zerovalent metals (such as zerovalent iron, zerovalent zinc, etc.), bivalent iron ions, dithionite, sodium sulfide, hydrogen sulfide, etc., can serve as reducing agents to permit the chlorine-containing organic solvents to be reduced to a less toxic material or an environmentally safe material. However, such reducing agents are normally in a solid state, and thus the contact area between the reducing agents and the chlorine-containing organic solvents is limited. If such reducing agents are in the form of fine particles, they will have an increased surface area, hence the risk of spontaneous combustion.
U.S. Pat. No. 6,221,002 has disclosed that a sufficient amount of ascorbic acid can be used as a reducing agent to chemically reduce hexavalent chromium in COPR (chromite ore processing residue) contaminated soils to a lower valence state.